Soft copolymers with high impact strength

ABSTRACT

The present invention is directed to a new heterophasic propylene copolymer (RAHECO) and an injection molded article comprising the heterophasic propylene copolymer (RAHECO) as well as a thin wall packaging comprising the heterophasic propylene copolymer (RAHECO). The present invention is further directed to the use of the heterophasic propylene copolymer (RAHECO) for improving the toughness of an injection molded article.

The present invention is directed to a new heterophasic propylenecopolymer (RAHECO) and an injection molded article comprising theheterophasic propylene copolymer (RAHECO) as well as a thin wallpackaging container comprising the heterophasic propylene copolymer(RAHECO). The present invention is further directed to the use of theheterophasic propylene copolymer (RAHECO) for improving the toughness ofan injection molded article.

In the field of thin-wall packaging it is of great importance to have awell flowing material with good mechanical properties, i.e. a hightensile modulus and good impact strength. The good flowability is neededfor achieving a good processability in various manufacturing methods ofarticles, e.g. in the injection molding processes, thereby allowing thehigh production speed required in this mass production market. Themechanical properties are also critical in view of the thin-walledarticles. Particularly, in the field of containers there is a need tohold the content such as food contained therein as well as havingsufficient stiffness to be stacked. Furthermore, the materials shouldalso withstand mechanical impact damage, which is frequently incurred bye.g. dropping the articles.

Still further, also the optical properties such as the haze should beacceptable. Particularly, a good balance between optical and mechanicalproperties such as toughness and haze is desirable.

In this regard, it is well known that the toughness of a heterophasicsystems can be improved by increasing the amount as well as themolecular weight, i.e. the intrinsic viscosity, of the elastomericpropylene copolymer (E) dispersed in the matrix (M) of the heterophasicpropylene copolymer.

However, there is still a need in the art for providing a heterophasicsystem having improved mechanical properties such as toughness incombination with good optical properties are required.

Thus, it is an object of the present invention to provide a softheterophasic propylene copolymer with an optimized or improved balancebetween mechanical and optical properties.

The finding of the present invention is to provide a heterophasicpropylene copolymer which must be produced in the presence of aZiegler-Natta catalyst containing an internal donor (ID) not belongingto the class of phthalic acid esters. With such a catalyst aheterophasic propylene copolymer can be produced having an optimized orimproved toughness in combination with good optical properties, such ashaze.

Accordingly, the present invention is directed to a heterophasicpropylene copolymer (RAHECO), said heterophasic propylene copolymer(RAHECO) comprises a matrix (M) being a random propylene copolymer(R-PP) and an elastomeric propylene copolymer (E) dispersed in saidmatrix (M), wherein the heterophasic propylene copolymer (RAHECO) has

-   a) a melt flow rate MFR₂ (230° C.) measured according to ISO 1133 in    the range of 0.3 to 20.0 g/10 min,-   b) a xylene cold soluble content (XCS) determined according ISO    16152 (25° C.) in the range of 16.0 to 50.0 wt.-%,-   c) a total comonomer content in the range of 11.5 to 21.0 mol-%, and    wherein further the heterophasic propylene copolymer (RAHECO)    (i) is free of phthalic acid esters as well as their respective    decomposition products and/or    (ii) has a Charpy notched impact strength as defined by in-equation    (III)

NIS>60.0−23.0×In(MFR)  (III)

-   -   wherein    -   “NIS” is the Charpy notched impact strength according to ISO        179-1eA:2000 at 23° C. [in kJ/m²] of the heterophasic propylene        copolymer (RAHECO), and “MFR” is the MFR₂ (230° C./2.16 kg) [in        g/10 min] of the heterophasic propylene copolymer (RAHECO).

It has surprisingly been found out that such heterophasic propylenecopolymer (RAHECO) has optimized or improved mechanical properties suchas toughness in combination with good optical properties, such as haze.

In one embodiment of the present invention, the xylene cold solublecontent (XCS) has

-   i) a comonomer content in the range of 36.5 to 50.0 mol-%, and/or-   ii) an intrinsic viscosity (IV) determined according to DIN ISO    1628/1, (in Decalin at 135° C.) in the range of 2.0 to 4.5 dl/g.

In another embodiment of the present invention, the random propylenecopolymer (R-PP) has

-   i) before vis-breaking a melt flow rate MFR₂ (230° C.) measured    according to ISO 1133 in the range of 3.0 to 8.0 g/10 min, and/or-   ii) a comonomer content in the range of 4.4 to 9.0 mol-%.

In still another embodiment of the present invention, the xylene coldinsoluble fraction (XCI) has a relative content of isolated to blockethylene sequences (I(E)) in the range of 50.0 to 65.0%, like 53.0 to65.0%, wherein the I(E) content is defined by equation (I)

$\begin{matrix}{{I(E)} = {\frac{fPEP}{\left( {{fEEE} + {fPEE} + {fPEP}} \right)} \times 100}} & (I)\end{matrix}$

whereinI(E) is the relative content of isolated to block ethylene sequences [in%];fPEP is the mol fraction of propylene/ethylene/propylene sequences (PEP)in the xylene cold insoluble fraction (XCI) of the heterophasicpropylene copolymer (RAHECO);fPEE is the mol fraction of propylene/ethylene/ethylene sequences (PEE)and of ethylene/ethylene/propylene sequences (EEP) in the xylene coldinsoluble fraction (XCI) of the heterophasic propylene copolymer(RAHECO);fEEE is the mol fraction of ethylene/ethylene/ethylene sequences (EEE)in the xylene cold insoluble fraction (XCI) of the heterophasicpropylene copolymer (RAHECO), wherein all sequence concentrations beingbased on a statistical triad analysis of ¹³C-NMR data.

In yet another embodiment of the present invention, the comonomers ofthe random propylene copolymer (R-PP) and/or the comonomers of theelastomeric propylene copolymer (E) are ethylene and/or C₄ to C₈α-olefin.

In one embodiment of the present invention, the heterophasic propylenecopolymer (RAHECO) comprises 65.0 to 90.0 wt.-%, like 75.0 to 90.0wt.-%, more preferably 65.0 to 88.0 wt.-%, like 75 to 88.0 wt.-%, basedon the total weight of the heterophasic propylene copolymer (RAHECO), ofthe random propylene copolymer (R-PP) and 10.0 to 35.0 wt.-%, like 10.0to 25.0 wt.-%, more preferably 12.0 to 35.0 wt.-%, like 12.0 to 25.0wt.-%, based on the total weight of the heterophasic propylene copolymer(RAHECO), of the elastomeric propylene copolymer (E).

In another embodiment of the present invention, the heterophasicpropylene copolymer (RAHECO) has been visbroken. It is preferred thatthe heterophasic propylene copolymer (RAHECO) has been visbroken with avisbreaking ratio (VR) as defined by in-equation (II)

$\begin{matrix}{1.5 \leq \frac{{MFRfinal} - {MFRinitial}}{MFRinitial} \leq 30.0} & ({II})\end{matrix}$

wherein“MFRfinal” is the MFR₂ (230° C./2.16 kg) of the heterophasic propylenecopolymer (RAHECO) after visbreaking and“MFRinitial” is the MFR₂ (230° C./2.16 kg) of the heterophasic propylenecopolymer (RAHECO) before visbreaking

In one embodiment of the present invention, the heterophasic propylenecopolymer (RAHECO) has been polymerized in the presence of

-   a) a Ziegler-Natta catalyst (ZN-C) comprising compounds (TC) of a    transition metal of Group 4 to 6 of IUPAC, a Group 2 metal    compound (MC) and an internal donor (ID), wherein said internal    donor (ID) is a non-phthalic compound, preferably is a non-phthalic    acid ester;-   b) optionally a co-catalyst (Co), and-   c) optionally an external donor (ED).

It is preferred that a) the internal donor (ID) is selected fromoptionally substituted malonates, maleates, succinates, glutarates,cyclohexene-1,2-dicarboxylates, benzoates and derivatives and/ormixtures thereof, preferably the internal donor (ID) is a citraconate;b) the molar-ratio of co-catalyst (Co) to external donor (ED) [Co/ED] is5 to 45.

In yet another embodiment of the present invention, the heterophasicpropylene copolymer (RAHECO) comprising a matrix (M) being a randompropylene copolymer (R-PP) and an elastomeric propylene copolymer (E)dispersed in said matrix (M) is produced in a multistage processcomprising at least two reactors connected in series.

It is preferred that

-   (a) in a first reactor propylene and ethylene and/or C₄ to C₈    α-olefin are polymerized obtaining a first propylene copolymer    fraction (R-PP1),-   (b) transferring said first propylene copolymer fraction (R-PP1) in    a second reactor,-   (c) polymerizing in said second reactor in the presence of the first    propylene copolymer fraction (R-PP1) propylene and ethylene and/or    C₄ to C₈ α-olefin obtaining a second propylene copolymer fraction    (R-PP2), said first propylene copolymer fraction (R-PP1) and said    second propylene copolymer fraction (R-PP2) form the matrix (R-PP),-   (d) transferring said matrix (M) in a third reactor,-   (e) polymerizing in said third reactor in the presence of the    matrix (M) propylene and ethylene and/or C₄ to C₈ α-olefin obtaining    an elastomeric propylene copolymer (E), said matrix (M) and said    elastomeric propylene copolymer (E) form the heterophasic propylene    copolymer (RAHECO).

In one embodiment of the present invention, the heterophasic propylenecopolymer (RAHECO) has a flexural modulus measured according to ISO 178in the range of 300 to 700 MPa.

The present invention is also directed to an injection molded articlecomprising the heterophasic propylene copolymer (RAHECO).

The present invention is further directed to a thin wall packaging,preferably a thin wall packaging made by injection molding, comprisingthe heterophasic propylene copolymer (RAHECO).

The present invention is even further directed to an use of theheterophasic propylene copolymer (RAHECO) for improving the toughness ofan injection molded article, wherein the improvement is accomplishedwhen the article has a Charpy notched impact strength as defined byin-equation (III)

NIS>60.0−23.0×In(MFR)  (III)

wherein“NIS” is the Charpy notched impact strength according to ISO179-1eA:2000 at 23° C. [in kJ/m²] of the heterophasic propylenecopolymer (RAHECO), and“MFR” is the MFR₂ (230° C./2.16 kg) [in g/10 min] of the heterophasicpropylene copolymer (RAHECO).

In the following, the present invention is described in more detail.

The instant heterophasic propylene copolymer (RAHECO) is especiallyfeatured by its specific mechanical and optical properties.

Accordingly, it is preferred that the heterophasic propylene copolymer(RAHECO) has a flexural modulus measured according to ISO 178 in therange of 300 to 700 MPa. For example, the heterophasic propylenecopolymer (RAHECO) has a flexural modulus measured according to ISO 178in the range of 330 to 650 MPa or in the range of 350 to 600 MPa.

In particular, the instant heterophasic propylene copolymer (RAHECO)features an improved toughness, which can be preferably described asfunction of processability. Thus, the instant heterophasic propylenecopolymer (RAHECO) preferably features a Charpy notched impact strengthas defined by in-equation (III), more preferably by in-equation (IIIa),still more preferably by in-equation (IIIb),

NIS>60.0−23.0×In(MFR)  (III)

NIS>63.0−23.0×In(MFR)  (IIIa)

NIS>65.0−23.0×In(MFR)  (IIIb)

wherein“NIS” is the Charpy notched impact strength according to ISO179-1eA:2000 at 23° C. [in kJ/m²] of the heterophasic propylenecopolymer (RAHECO), and“MFR” is the MFR₂ (230° C./2.16 kg) [in g/10 min] of the heterophasicpropylene copolymer (RAHECO).

For example, the instant heterophasic propylene copolymer (RAHECO)features a Charpy notched impact strength according to ISO 179-1eA:2000at 23° C. in the range of 5.0 to 90.0 kJ/m², preferably in the range of10.0 to 90.0 kJ/m².

With regard to the optical properties it is preferred that theheterophasic propylene copolymer (RAHECO) has a haze according to ASTM D1003-00 measured on a 1 mm thick injection molded specimen in the rangeof 78.0 to 100.0%, preferably in the range of 80.0 to 100.0%.

In one embodiment of the present invention, the heterophasic propylenecopolymer (RAHECO) has

-   a) a flexural modulus measured according to ISO 178 in the range of    300 to 700 MPa, preferably in the range of 330 to 650 MPa and most    preferably in the range of 350 to 600 MPa, and-   b) a Charpy notched impact strength as defined by in-equation (III),    more preferably by in-equation (IIIa), still more preferably by    in-equation (IIIb),

NIS>60.0−23.0×In(MFR)  (III)

NIS>63.0−23.0×In(MFR)  (IIIa)

NIS>65.0−23.0×In(MFR)  (IIIb)

-   -   wherein    -   “NIS” is the Charpy notched impact strength according to ISO        179-1eA:2000 at 23° C. [in kJ/m²] of the heterophasic propylene        copolymer (RAHECO), and    -   “MFR” is the MFR₂ (230° C./2.16 kg) [in g/10 min] of the        heterophasic propylene copolymer (RAHECO).

Preferably not only the heterophasic propylene copolymer (RAHECO) isfeatured by the specific values of toughness, flexural modulus and haze,but also the injection molded article comprising the heterophasicpropylene copolymer (RAHECO) and thin wall packaging comprising theheterophasic propylene copolymer (RAHECO) when measured under the sameconditions as indicated above. Accordingly the above indicated values oftoughness, flexural modulus and haze are equally but proportionallyapplicable for the injection molded article and thin wall packaging.

The heterophasic propylene copolymer (RAHECO) according to thisinvention comprises a matrix (M) being a random propylene copolymer(R-PP) and dispersed therein an elastomeric propylene copolymer (E).Thus the matrix (M) contains (finely) dispersed inclusions being notpart of the matrix (M) and said inclusions contain the elastomericpropylene copolymer (E). The term inclusion indicates that the matrix(M) and the inclusion form different phases within the heterophasicpropylene copolymer (RAHECO). The presence of second phases or the socalled inclusions are for instance visible by high resolutionmicroscopy, like electron microscopy or atomic force microscopy, or bydynamic mechanical thermal analysis (DMTA). Specifically in DMTA thepresence of a multiphase structure can be identified by the presence ofat least two distinct glass transition temperatures.

Preferably, the heterophasic propylene copolymer (RAHECO) according tothis invention comprises as polymer components only the random propylenecopolymer (R-PP) and the elastomeric propylene copolymer (E). In otherwords, the heterophasic propylene copolymer (RAHECO) may contain furtheradditives but no other polymer in an amount exceeding 5.0 wt.-%, morepreferably exceeding 3.0 wt.-%, like exceeding 1.0 wt.-%, based on thetotal heterophasic propylene copolymer (RAHECO). One additional polymerwhich may be present in such low amounts is a polyethylene which is aby-reaction product obtained by the preparation of the heterophasicpropylene copolymer (RAHECO). Accordingly, it is in particularappreciated that the instant heterophasic propylene copolymer (RAHECO)contains only the random propylene copolymer (R-PP), the elastomericpropylene copolymer (E) and optionally polyethylene in amounts asmentioned in this paragraph.

The heterophasic propylene copolymer (RAHECO) according to thisinvention can have a broad range of melt flow rate. Accordingly, theheterophasic propylene copolymer (HECO) has a melt flow rate MFR₂ (230°C.) in the range of 0.3 to 20.0 g/10 min, preferably in the range of 0.3to 18.0 g/10 min, more preferably in the range of 0.4 to 16.0 g/10 min.

Preferably, it is desired that the heterophasic propylene copolymer(RAHECO) is thermo mechanically stable. Accordingly, it is appreciatedthat the heterophasic propylene copolymer (RAHECO) has a meltingtemperature of at least 130° C., more preferably in the range of 130 to160° C., still more preferably in the range of 130 to 155° C.

Typically, the heterophasic propylene copolymer (RAHECO) has a ratherlow crystallization temperature, i.e. of not more than 110° C., morepreferably in the range of 95 to 110° C., still more preferably in therange of 100 to 108° C. These values are especially applicable in casethe heterophasic propylene copolymer (RAHECO) is not α-nucleated.

The heterophasic propylene copolymer (RAHECO) comprises apart frompropylene also comonomers. Preferably the heterophasic propylenecopolymer (RAHECO) comprises apart from propylene ethylene and/or C₄ toC₈ α-olefins. Accordingly the term “propylene copolymer” according tothis invention is understood as a polypropylene comprising, preferablyconsisting of, units derivable from

(a) propyleneand(b) ethylene and/or C₄ to C₈ α-olefins.

Thus, the heterophasic propylene copolymer (RAHECO), i.e. the randompropylene copolymer (R-PP) such as the first propylene copolymerfraction (R-PP1) and the second propylene copolymer fraction (R-PP2), aswell as the elastomeric propylene copolymer (E), comprises monomerscopolymerizable with propylene, for example comonomers such as ethyleneand/or C₄ to C₈ α-olefins, in particular ethylene and/or C₄ to C₈α-olefins, e.g. 1-butene and/or 1-hexene. Preferably, the heterophasicpropylene copolymer (RAHECO) according to this invention comprises,especially consists of, monomers copolymerizable with propylene from thegroup consisting of ethylene, 1-butene and 1-hexene. More specifically,the heterophasic propylene copolymer (RAHECO) of this inventioncomprises—apart from propylene—units derivable from ethylene and/or1-butene. In a preferred embodiment, the heterophasic propylenecopolymer (RAHECO) according to this invention comprises units derivablefrom ethylene and propylene only. Still more preferably the randompropylene copolymer (R-PP), i.e. the first propylene copolymer fraction(R-PP1) and the second propylene copolymer fraction (R-PP2), as well asthe elastomeric propylene copolymer (E) of the heterophasic propylenecopolymer (RAHECO) contain the same comonomers, like ethylene.

Accordingly, the elastomeric propylene copolymer (E) is preferably anethylene propylene rubber (EPR), whereas the random propylene copolymer(R-PP) is a random ethylene propylene copolymer (R-PP).

Additionally, it is appreciated that the heterophasic propylenecopolymer (RAHECO) preferably has a moderate total comonomer contentwhich contributes to the softness of the material. Thus, it is requiredthat the comonomer content of the heterophasic propylene copolymer(RAHECO) is in the range from 11.5 to 21.0 mol-%, preferably in therange from 12.9 to 21.0 mol-%, more preferably in the range from 12.9 to18.3 mol-%, yet more preferably in the range from 14.3 to 20.0 mol-%.

The xylene cold soluble (XCS) fraction measured according to accordingISO 16152 (25° C.) of the heterophasic propylene copolymer (RAHECO) isin the range from 16.0 to 50.0 wt.-%, preferably in the range from 16.0to 40.0 wt.-%, more preferably in the range from 16.0 to 35.0 wt.-%,still more preferably in the range from 17.0 to 28.0 wt.-%.

Further it is appreciated that the xylene cold soluble (XCS) fraction ofthe heterophasic propylene copolymer (RAHECO) is specified by itsintrinsic viscosity. A low intrinsic viscosity (IV) value reflects a lowweight average molecular weight. For the present invention it isappreciated that the xylene cold soluble fraction (XCS) of theheterophasic propylene copolymer (RAHECO) has an intrinsic viscosity(IV) measured according to ISO 1628/1 (at 135° C. in decalin) in therange of 2.0 to 4.5 dl/g, preferably in the range of 2.2 to 4.5 dl/g,more preferably in the range of 2.4 to below 4.5 dl/g, and mostpreferably in the range of 2.4 to below 4.3 dl/g.

Additionally it is preferred that the comonomer content, i.e. ethylenecontent, of the xylene cold soluble (XCS) fraction of the heterophasicpropylene copolymer (RAHECO) is not more than 50.0 mol-%, morepreferably in the range of 36.8 to 50.0 mol-%, still more preferably inthe range of 36.8 to 47.9 mol-%, yet more preferably in the range of38.0 to 45.8 mol-%. The comonomers present in the xylene cold soluble(XCS) fraction are those defined above for the random propylenecopolymer (R-PP) and the elastomeric propylene copolymer (E),respectively. In one preferred embodiment the comonomer is ethyleneonly.

The heterophasic propylene copolymer (RAHECO) can be further defined byits individual components, i.e. the random propylene copolymer (R-PP)and the elastomeric propylene copolymer (E).

The random propylene copolymer (R-PP) comprises monomers copolymerizablewith propylene, for example comonomers such as ethylene and/or C₄ to C₈α-olefins, in particular ethylene and/or C₄ to C₆ α-olefins, e.g.1-butene and/or 1-hexene. Preferably the random propylene copolymer(R-PP) according to this invention comprises, especially consists of,monomers copolymerizable with propylene from the group consisting ofethylene, 1-butene and 1-hexene. More specifically the random propylenecopolymer (R-PP) of this invention comprises—apart from propylene—unitsderivable from ethylene and/or 1-butene. In a preferred embodiment therandom propylene copolymer (R-PP) comprises units derivable fromethylene and propylene only.

As mentioned above the random propylene copolymer (R-PP) is featured bya moderate comonomer content. Accordingly, the comonomer content of therandom propylene copolymer (R-PP) is in the range of 4.4 to 9.0 mol-%,yet more preferably in the range of 4.7 to 8.7 mol-%, still morepreferably in the range of 5.0 to 8.7 mol-%.

The term “random” indicates that the comonomers of the random propylenecopolymer (R-PP), as well as of the first propylene copolymer fraction(R-PP1) and the second propylene copolymer fraction (R-PP2) are randomlydistributed within the propylene copolymers. The term random isunderstood according to IUPAC (Glossary of basic terms in polymerscience; IUPAC recommendations 1996).

The random propylene copolymer (R-PP) preferably comprises at least twopolymer fractions, like two or three polymer fractions, all of them arepropylene copolymers. Even more preferred the random propylene copolymer(R-PP) comprises, preferably consists of, a first propylene copolymerfraction (R-PP1) and a second propylene copolymer fraction (R-PP2). Itis preferred that the first propylene copolymer fraction (R-PP1) is thecomonomer lean fraction whereas the second propylene copolymer fraction(R-PP2) is the comonomer rich fraction.

Concerning the comonomers used for the first propylene copolymerfraction (R-PP1) and second propylene copolymer fraction (R-PP2)reference is made to the comonomers of the random propylene copolymer(R-PP). Preferably the first propylene copolymer fraction (R-PP1) andthe second propylene copolymer fraction (R-PP2) contain the samecomonomers, like ethylene.

It is preferred that the random propylene copolymer (R-PP) is featuredby its relative content of isolated to block ethylene sequences (I(E)).According to the present invention the isolated to block ethylenesequences (I(E)) of the random propylene copolymer (R-PP) is measured onthe xylene cold insoluble fraction (XCI) of the heterophasic propylenecopolymer (RAHECO). Accordingly the xylene cold insoluble fraction (XCI)of the heterophasic propylene copolymer (RAHECO) has an isolated toblock ethylene sequences (I(E)) in the range of 50.0 to 65.0%, like 53.0to 65.0%, more preferably in the range of 54.0 to 63.0%, like 55.0 to62.0%.

The I(E) content [%] is defined by in-equation (I)

$\begin{matrix}{{I(E)} = {\frac{fPEP}{\left( {{fEEE} + {fPEE} + {fPEP}} \right)} \times 100}} & (I)\end{matrix}$

whereinI(E) is the relative content of isolated to block ethylene sequences [in%];fPEP is the mol fraction of propylene/ethylene/propylene sequences (PEP)in the xylene cold insoluble fraction (XCI) of the heterophasicpropylene copolymer (RAHECO);fPEE is the mol fraction of propylene/ethylene/ethylene sequences (PEE)and of ethylene/ethylene/propylene sequences (EEP) in the xylene coldinsoluble fraction (XCI) of the heterophasic propylene copolymer(RAHECO);fEEE is the mol fraction of ethylene/ethylene/ethylene sequences (EEE)in the xylene cold insoluble fraction (XCI) of the heterophasicpropylene copolymer (RAHECO), wherein all sequence concentrations beingbased on a statistical triad analysis of ¹³C-NMR data.

The random propylene copolymer (R-PP) according to this invention has amelt flow rate MFR₂ (230° C./2.16 kg) before visbreaking measuredaccording to ISO 1133 in the range of 0.4 to 7.0 g/10 min, morepreferably in the range of 0.5 to 6.5 g/10 min, still more preferably inthe range of 0.6 to 6.0 g/10 min.

The heterophasic propylene copolymer (RAHECO) preferably comprises 60 to90 wt.-%, like 60.0 to 87.0 wt.-%, more preferably 65.0 to 90.0 wt.-%,like 75.0 to 90.0 wt.-%, still more preferably 65.0 to 88.0 wt.-%, like75 to 88.0 wt.-%, of the random propylene copolymer (R-PP), based on thetotal weight of the heterophasic propylene copolymer (RAHECO).

Additionally, the heterophasic propylene copolymer (RAHECO) preferablycomprises, like consist of, 10 to 40 wt.-%, like 13.0 to 40.0 wt.-%,more preferably 10.0 to 35.0 wt.-%, like 10.0 to 25.0 wt.-%, still morepreferably 12.0 to 35.0 wt.-%, like 12.0 to 25.0 wt.-%, of theelastomeric propylene copolymer (E), based on the total weight of theheterophasic propylene copolymer (RAHECO).

Thus, it is appreciated that the heterophasic propylene copolymer(RAHECO) preferably comprises, more preferably consists of, 65.0 to 88.0wt.-% of the random propylene copolymer (R-PP) and 12.0 to 35.0 wt.-% ofthe elastomeric propylene copolymer (E), based on the total weight ofthe heterophasic propylene copolymer (RAHECO).

Accordingly, a further component of the heterophasic propylene copolymer(RAHECO) is the elastomeric propylene copolymer (E) dispersed in thematrix (M). Concerning the comonomers used in the elastomeric propylenecopolymer (E) it is referred to the information provided for theheterophasic propylene copolymer (RAHECO). Accordingly the elastomericpropylene copolymer (E) comprises monomers copolymerizable withpropylene, for example comonomers such as ethylene and/or C₄ to C₈α-olefins, in particular ethylene and/or C₄ to C₆ α-olefins, e.g.1-butene and/or 1-hexene. Preferably, the elastomeric propylenecopolymer (E) comprises, especially consists of, monomerscopolymerizable with propylene from the group consisting of ethylene,1-butene and 1-hexene. More specifically, the elastomeric propylenecopolymer (E) comprises—apart from propylene—units derivable fromethylene and/or 1-butene. Thus, in an especially preferred embodimentthe elastomeric propylene copolymer (E) comprises units derivable fromethylene and propylene only.

The comonomer content, like ethylene content, of the elastomericpropylene copolymer (E) preferably is in the range of 50.0 to 80.0mol-%, more preferably in the range of 53.0 to 78.0 mol-%, still morepreferably in the range of 55.0 to 76.0 mol.

As mentioned above multiphase structures can be identified by thepresence of at least two distinct glass transition temperatures. Thehigher glass transition temperature Tg(1) represents the matrix whereasthe lower glass transition temperature Tg(2) reflects the elastomericpropylene copolymer (E) of the heterophasic propylene copolymer(RAHECO).

Accordingly, it is one preferred requirement of the present invention,that the heterophasic propylene copolymer (RAHECO) has a glasstransition temperature Tg(2) fulfilling the in-equation (IV), morepreferably the in-equation (IVa), still more preferably in-equation(IVb),

Tg(2)>20.0−2.0×C(XCS)  (IV)

Tg(2)>19.0−2.0×C(XCS)  (IVa)

Tg(2)>18.0−2.0×C(XCS)  (IVb)

whereinTg(2) is the glass transition temperature of the heterophasic propylenecopolymer (RAHECO);C(XCS) is the comonomer content [in mol-%] of the xylene cold solublecontent (XCS) of the heterophasic propylene copolymer (RAHECO).

Preferrably said glass transition temperature Tg(2) is below −35° C.,more preferably is in the range of −62 to −45° C., still more preferablyin the range of −60 to −50° C. It is especially preferred that theheterophasic propylene copolymer (RAHECO) has a glass transitiontemperature Tg(2) as mentioned in this paragraph and fulfilling thein-equation (IV) as defined in the present invention.

It is further appreciated that the the heterophasic propylene copolymer(RAHECO) according to this invention has additionally a first glasstransition temperature Tg(1) (representing the matrix (M) of theheterophasic propylene copolymer (RAHECO)) in the range of −12 to +2°C., more preferably in the range of −10 to +2° C.

Accordingly the the first glass transition temperature Tg(1) ispreferably above the second glass transition temperature Tg(2). Stillmore preferably the difference between the first glass transitiontemperature Tg(1) and second glass transition temperature Tg(2) is atleast 40° C., more preferably at least 45° C., yet more preferably inthe range of 40 to 55° C., still more preferably in the range of 45 to52° C.

The heterophasic propylene copolymer (RAHECO) as defined in the instantinvention may contain up to 5.0 wt.-% additives, like nucleating agentsand antioxidants, as well as slip agents and antiblocking agents.Preferably the additive content (without α-nucleating agents) is below3.0 wt.-%, like below 1.0 wt.-%.

In one embodiment of the present invention, the heterophasic propylenecopolymer (RAHECO) comprises a nucleating agent, more preferably aα-nucleating agent. Even more preferred the present invention is free ofβ-nucleating agents. The α-nucleating agent is preferably selected fromthe group consisting of

-   (i) salts of monocarboxylic acids and polycarboxylic acids, e.g.    sodium benzoate or aluminum tert-butylbenzoate, and-   (ii) dibenzylidenesorbitol (e.g. 1,3:2,4 dibenzylidenesorbitol) and    C₁-C₈-alkyl-substituted dibenzylidenesorbitol derivatives, such as    methyldibenzylidenesorbitol, ethyldibenzylidenesorbitol or    dimethyldibenzylidenesorbitol (e.g. 1,3:2,4 di(methylbenzylidene)    sorbitol), or substituted nonitol-derivatives, such as    1,2,3,-trideoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene]-nonitol,    and-   (iii) salts of diesters of phosphoric acid, e.g. sodium    2,2′-methylenebis (4, 6,-di-tert-butylphenyl) phosphate or    aluminium-hydroxy-bis[2,2′-methylene-bis(4,6-di-t-butylphenyl)phosphate],    and-   (iv) vinylcycloalkane polymer and vinylalkane polymer, and-   (v) mixtures thereof

Such additives are generally commercially available and are described,for example, in “Plastic Additives Handbook”, 5th edition, 2001 of HansZweifel.

Preferably the heterophasic propylene copolymer (RAHECO) contains up to2.0 wt.-% of the α-nucleating agent. In a preferred embodiment, theheterophasic propylene copolymer (RAHECO) contains not more than 3000ppm, more preferably of 1 to 3000 ppm, more preferably of 5 to 2000 ppmof a α-nucleating agent, in particular selected from the groupconsisting of dibenzylidenesorbitol (e.g. 1,3:2,4 dibenzylidenesorbitol), dibenzylidenesorbitol derivative, preferablydimethyldibenzylidenesorbitol (e.g. 1,3:2,4 di(methylbenzylidene)sorbitol), or substituted nonitol-derivatives, such as1,2,3,-trideoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene]-nonitol,vinylcycloalkane polymer, vinylalkane polymer, and mixtures thereof

The heterophasic propylene copolymer (RAHECO) according to thisinvention is preferably produced in the presence of

-   (a) a Ziegler-Natta catalyst (ZN-C) comprising compounds (TC) of a    transition metal of Group 4 to 6 of IUPAC, a Group 2 metal    compound (MC) and an internal donor (ID), wherein said internal    donor (ID) is a non-phthalic compound, preferably is a non-phthalic    acid ester and still more preferably is a diester of non-phthalic    dicarboxylic acids;-   (b) optionally a co-catalyst (Co), and-   (c) optionally an external donor (ED).

It is preferred that the internal donor (ID) is selected from optionallysubstituted malonates, maleates, succinates, glutarates,cyclohexene-1,2-dicarboxylates, benzoates and derivatives and/ormixtures thereof, preferably the internal donor (ID) is a citraconate.Additionally or alternatively, the molar-ratio of co-catalyst (Co) toexternal donor (ED) [Co/ED] is 5 to 45.

It is thus one requirement of the present invention that theheterophasic propylene copolymer (RAHECO) is free of phthalic acidesters as well as their respective decomposition products, i.e. phthalicacid esters, typically used as internal donor of Ziegler-Natta (ZN)catalysts. Preferably, the heterophasic propylene copolymer (RAHECO) isfree of phthalic compounds as well as their respective decompositionproducts, i.e. phthalic compounds typically used as internal donor ofZiegler-Natta (ZN) catalysts.

The term “free of” phthalic acid esters, preferably phthalic compounds,in the meaning of the present invention refers to a heterophasicpropylene copolymer (RAHECO) in which no phthalic acid esters as well norespective decomposition products, preferably no phthalic compounds aswell as no respective decomposition products at all, are detectable.

As the heterophasic propylene copolymer (RAHECO) comprises the randompropylene copolymer (R-PP) and the elastomeric propylene copolymer (E),the individual components are preferably also free of phthalic acidesters as well as their respective decomposition products, morepreferably of phthalic compounds as well as their respectivedecomposition products.

The heterophasic propylene copolymer (RAHECO) comprises a matrix (M)being a random propylene copolymer (R-PP) and an elastomeric propylenecopolymer (E) dispersed in said matrix (M). Preferably the randompropylene copolymer (R-PP) comprises at least two polymer fractions,like two or three polymer fractions, all of them are propylenecopolymers. Even more preferred the random propylene copolymer (R-PP)comprises, preferably consists of, a first propylene copolymer fraction(R-PP1) and a second propylene copolymer fraction (R-PP2).

Further it is preferred that the first propylene copolymer fraction(R-PP1) and the second propylene copolymer fraction (R-PP2) have nearbythe same melt flow rate. Accordingly it is preferred that differencebetween the melt flow rate of the random propylene copolymer (R-PP) andthe first propylene copolymer fraction (R-PP1)[MFR(Pre-R-PP)−MFR(Pre-R-PP1)] is below +/−1.5 g/10 min, more preferably+/−1.0 g/10 min, yet more preferably +/−0.5 g/10 min. Thus, in oneembodiment the first propylene copolymer fraction (R-PP1) and the secondpropylene copolymer fraction (R-PP2) have a melt flow rate MFR₂ (230°C.) in the range of 0.4 to 7.0 g/10 min

In one embodiment of the present invention, the heterophasic propylenecopolymer (RAHECO) has been visbroken.

The visbroken heterophasic propylene copolymer (RAHECO) preferably has ahigher melt flow rate than the non-visbroken heterophasic propylenecopolymer (RAHECO).

Accordingly, the heterophasic propylene copolymer (RAHECO) beforevisbreaking preferably has a melt flow rate MFR₂ (230° C.) in the rangeof 0.3 to 5.0 g/10 min. For example, the melt flow rate (230° C./2.16kg) of the heterophasic propylene copolymer (RAHECO) before visbreakingis from 0.3 to 4.0 g/10 min, like from 0.3 to 3.0 g/10 min.

Furthermore, the melt flow rate (230° C./2.16 kg) of the heterophasicpropylene copolymer (RAHECO) after visbreaking is higher, i.e. from 0.5to 20.0 g/10 min. For example, the melt flow rate (230° C./2.16 kg) ofthe heterophasic propylene copolymer (RAHECO) after visbreaking is from0.7 to 18.0 g/10 min, like from 1.0 to 15.0 g/10 min.

In one embodiment of the present invention, the heterophasic propylenecopolymer (RAHECO) has been visbroken with a visbreaking ratio (VR) asdefined by equation (I)

$\begin{matrix}{1.5 \leq \frac{{MFRfinal} - {MFRinitial}}{MFRinitial} \leq 30.0} & ({II})\end{matrix}$

wherein“MFRfinal” is the MFR₂ (230° C./2.16 kg) of the heterophasic propylenecopolymer (RAHECO) after visbreaking and“MFRinitial” is the MFR₂ (230° C./2.16 kg) of the heterophasic propylenecopolymer (RAHECO) before visbreaking

Preferred mixing devices suited for visbreaking are discontinuous andcontinuous kneaders, twin screw extruders and single screw extruderswith special mixing sections and co-kneaders.

By visbreaking the heterophasic propylene copolymer (RAHECO) with heator at more controlled conditions with peroxides, the molar massdistribution (MWD) becomes narrower because the long molecular chainsare more easily broken up or scissored and the molar mass M, willdecrease, corresponding to an MFR₂ increase. The MFR₂ increases withincrease in the amount of peroxide which is used.

Such visbreaking may be carried out in any known manner, like by using aperoxide visbreaking agent. Typical visbreaking agents are2,5-dimethyl-2,5-bis(tert.butyl-peroxy)hexane (DHBP) (for instance soldunder the tradenames Luperox 101 and Trigonox 101),2,5-dimethyl-2,5-bis(tert.butyl-peroxy)hexyne-3 (DYBP) (for instancesold under the tradenames Luperox 130 and Trigonox 145),dicumyl-peroxide (DCUP) (for instance sold under the tradenames LuperoxDC and Perkadox BC), di-tert.butyl-peroxide (DTBP) (for instance soldunder the tradenames Trigonox B and Luperox Di),tert.butyl-cumyl-peroxide (BCUP) (for instance sold under the tradenamesTrigonox T and Luperox 801) and bis (tert.butylperoxy-isopropyl)benzene(DIPP) (for instance sold under the tradenames Perkadox 14S and LuperoxDC). Suitable amounts of peroxide to be employed in accordance with thepresent invention are in principle known to the skilled person and caneasily be calculated on the basis of the amount of heterophasicpropylene copolymer (RAHECO) to be subjected to visbreaking, the MFR₂(230° C./2.16 kg) value of the heterophasic propylene copolymer (RAHECO)to be subjected to visbreaking and the desired target

MFR₂ (230° C./2.16 kg) of the product to be obtained. Accordingly,typical amounts of peroxide visbreaking agent are from 0.005 to 0.7wt.-%, more preferably from 0.01 to 0.4 wt.-%, based on the total amountof heterophasic propylene copolymer (RAHECO) employed.

Typically, visbreaking in accordance with the present invention iscarried out in an extruder, so that under the suitable conditions, anincrease of melt flow rate is obtained. During visbreaking, higher molarmass chains of the starting product are broken statistically morefrequently than lower molar mass molecules, resulting as indicated abovein an overall decrease of the average molecular weight and an increasein melt flow rate.

The inventive heterophasic propylene copolymer (RAHECO) is preferablyobtained by visbreaking the heterophasic propylene copolymer (RAHECO),preferably visbreaking by the use of peroxide.

More precisely, the inventive heterophasic propylene copolymer (RAHECO)may be obtained by visbreaking the heterophasic propylene copolymer(RAHECO), preferably by the use of peroxide as mentioned above, in anextruder.

After visbreaking the heterophasic propylene copolymer (RAHECO)according to this invention is preferably in the form of pellets orgranules. The instant heterophasic propylene copolymer (RAHECO) ispreferably used in pellet or granule form for the preparation of theinjection molded article.

The present invention is not only directed to the instant heterophasicpropylene copolymer (RAHECO) but also to injection molded articles madetherefrom. The injection molded articles preferably comprise at least 70wt.-%, more preferably at least 90 wt.-%, yet more preferably at least95 wt.-%, still more preferably consist of, a heterophasic propylenecopolymer (RAHECO) as defined herein.

Further present invention is also directed to thin wall packagingelements, like thin wall packaging elements produced by injectionmolding, comprising at least 70 wt.-%, more preferably at least 90wt.-%, yet more preferably at least 95 wt.-%, still more preferablyconsisting of, a heterophasic propylene copolymer (RAHECO) as definedherein.

The thin wall packaging elements, like thin wall packaging elementsproduced by injection molding, preferably have a thickness of equal orbelow 2 mm, preferably in the range of 0.2 to 2.0 mm. Said thin wallpackaging elements are preferably produced by injection molding. Furtherthe thin wall packaging elements are preferably selected from the groupconsisting of cups, boxes, trays, pails, buckets, bowls, lids, flaps,caps, CD covers, DVD covers and the like.

The present invention is also directed to the use of the heterophasicpropylene copolymer (RAHECO) in the manufacture of injected moldedarticles.

Further, the present invention is directed to the use of theheterophasic propylene copolymer as defined herein for improving thetoughness of an injection molded article. In particular, the improvementis accomplished when the article has a Charpy notched impact strength asdefined by in-equation (III); more preferably by in-equation (IIIa),still more preferably by in-equation (IIIb),

NIS>60.0−23.0×In(MFR)  (III)

NIS>63.0−23.0×In(MFR)  (IIIa)

NIS>65.0−23.0×In(MFR)  (IIIb)

wherein“NIS” is the Charpy notched impact strength according to ISO179-1eA:2000 at 23° C. [in kJ/m²] of the heterophasic propylenecopolymer (RAHECO), and“MFR” is the MFR₂ (230° C./2.16 kg) [in g/10 min] of the heterophasicpropylene copolymer (RAHECO).

For example, the improvement is accomplished when the instantheterophasic propylene copolymer (RAHECO) features a Charpy notchedimpact strength according to ISO 179-1eA:2000 at 23° C. in the range of5.0 to 90.0 kJ/m², preferably in the range of 10.0 to 90.0 kJ/m².

Additionally or alternatively, the improvement is accomplished when theheterophasic propylene copolymer (RAHECO) has a flexural modulusmeasured according to ISO 178 in the range of 300 to 700 MPa. Forexample, the heterophasic propylene copolymer (RAHECO) has a flexuralmodulus measured according to ISO 178 in the range of 330 to 650 MPa orin the range of 350 to 600 MPa.

Thus, in one embodiment the improvement is accomplished when theheterophasic propylene copolymer (RAHECO) has

-   a) a flexural modulus measured according to ISO 178 in the range of    300 to 700 MPa, preferably in the range of 330 to 650 MPa and most    preferably in the range of 350 to 600 MPa,-   and-   b) a Charpy notched impact strength as defined by in-equation (III);    more preferably by in-equation (IIIa), still more preferably by    in-equation (IIIb),

NIS>60.0−23.0×In(MFR)  (III)

NIS>63.0−23.0×In(MFR)  (IIIa)

NIS>65.0−23.0×In(MFR)  (IIIb)

-   -   wherein    -   “NIS” is the Charpy notched impact strength according to ISO        179-1eA:2000 at 23° C. [in kJ/m²] of the heterophasic propylene        copolymer (RAHECO), and    -   “MFR” is the MFR₂ (230° C./2.16 kg) [in g/10 min] of the        heterophasic propylene copolymer (RAHECO),    -   and

-   c) a haze according to ASTM D 1003-00 measured on a 1 mm thick    injection molded specimen in the range of 78.0 to 100.0% and most    preferably in the range of 80.0 to 100.0%.

The instant heterophasic propylene copolymer (RAHECO) is preferablyproduced in a multistage process comprising at least two reactorsconnected in series a heterophasic propylene copolymer (RAHECO)comprising a matrix (M) being a random propylene copolymer (PP) and anelastomeric propylene copolymer (E) dispersed in said matrix (M),

Further, the weight ratio between the first propylene copolymer fraction(R-PP1) and second propylene copolymer fraction (R-PP2) preferably is20:80 to 80:20, more preferably 25:75 to 75:25, still more preferably30:70 to 70:30.

Preferably the heterophasic propylene copolymer (RAHECO) is obtained bya sequential polymerization process comprising the steps of

-   (a) polymerizing in a first reactor propylene and ethylene and/or C₄    to C₈ α-olefin obtaining thereby a first propylene copolymer    fraction (R-PP1),-   (b) transferring said first propylene copolymer fraction (R-PP1) in    a second reactor,-   (c) polymerizing in said second reactor in the presence of the first    propylene copolymer fraction (R-PP1) propylene and ethylene and/or    C₄ to C₈ α-olefin obtaining a second propylene copolymer fraction    (R-PP2), said first propylene copolymer fraction (R-PP1) and said    second propylene copolymer fraction (R-PP2) form the matrix (PP),-   (d) transferring said matrix (M) in a third reactor,-   (e) polymerizing in said third reactor in the presence of the    matrix (M) propylene and ethylene and/or C₄ to C₈ α-olefin obtaining    an elastomeric propylene copolymer (E), said matrix (M) and said    elastomeric propylene copolymer (E) form the heterophasic propylene    copolymer (RAHECO).

For preferred embodiments of the heterophasic propylene copolymer(HECO), the random propylene copolymer (R-PP), the first propylenecopolymer fraction (R-PP1), the second propylene copolymer fraction(R-PP2), and the elastomeric copolymer (E) reference is made to thedefinitions given above.

The term “sequential polymerization process” indicates that theheterophasic propylene copolymer (HECO) is produced in at least two,like three, reactors connected in series. Accordingly the presentprocess comprises at least a first reactor, a second reactor, andoptionally a third reactor. The term “polymerization process” shallindicate that the main polymerization takes place. Thus in case theprocess consists of three polymerization reactors, this definition doesnot exclude the option that the overall process comprises for instance apre-polymerization step in a pre-polymerization reactor. The term“consist of” is only a closing formulation in view of the mainpolymerization process.

The first reactor is preferably a slurry reactor and can be anycontinuous or simple stirred batch tank reactor or loop reactoroperating in bulk or slurry. Bulk means a polymerization in a reactionmedium that comprises of at least 60% (w/w) monomer. According to thepresent invention the slurry reactor is preferably a (bulk) loopreactor.

The second reactor and the third reactor are preferably gas phasereactors. Such gas phase reactors can be any mechanically mixed or fluidbed reactors. Preferably the gas phase reactors comprise a mechanicallyagitated fluid bed reactor with gas velocities of at least 0.2 m/sec.Thus it is appreciated that the gas phase reactor is a fluidized bedtype reactor preferably with a mechanical stirrer.

Thus in a preferred embodiment the first reactor is a slurry reactor,like loop reactor, whereas the second reactor and the third reactor (R3)are gas phase reactors (GPR). Accordingly for the instant process atleast three, preferably three polymerization reactors, namely a slurryreactor, like loop reactor, a first gas phase reactor and a second gasphase reactor are connected in series are used. If needed prior to theslurry reactor a pre-polymerization reactor is placed.

A preferred multistage process is a “loop-gas phase”-process, such asdeveloped by Borealis A/S, Denmark (known as BORSTAR® technology)described e.g. in patent literature, such as in EP 0 887 379, WO92/12182 WO 2004/000899, WO 2004/111095, WO 99/24478, WO 99/24479 or inWO 00/68315.

A further suitable slurry-gas phase process is the Spheripol® process ofBasell.

Preferably, in the instant process for producing the heterophasicpropylene copolymer (RAHECO) as defined above the conditions for thefirst reactor, i.e. the slurry reactor, like a loop reactor, may be asfollows:

-   -   the temperature is within the range of 50° C. to 110° C.,        preferably between 60° C. and 100° C., more preferably between        68 and 95° C.,    -   the pressure is within the range of 20 bar to 80 bar, preferably        between 40 bar to 70 bar,    -   hydrogen can be added for controlling the molar mass in a manner        known per se.

Subsequently, the reaction mixture of the first reactor is transferredto the second reactor, i.e. gas phase reactor, where the conditions arepreferably as follows:

-   -   the temperature is within the range of 50° C. to 130° C.,        preferably between 60° C. and 100° C.,    -   the pressure is within the range of 5 bar to 50 bar, preferably        between 15 bar to 35 bar,    -   hydrogen can be added for controlling the molar mass in a manner        known per se.

The condition in the third reactor is similar to the second reactor.

The residence time can vary in the three reactor zones.

In one embodiment of the process for producing the heterophasicpropylene copolymer (RAHECO) the residence time in bulk reactor, e.g.loop is in the range 0.1 to 2.5 hours, e.g. 0.15 to 1.5 hours and theresidence time in gas phase reactor will generally be 0.2 to 6.0 hours,like 0.5 to 4.0 hours.

If desired, the polymerization may be effected in a known manner undersupercritical conditions in the first reactor, i.e. in the slurryreactor, like in the loop reactor, and/or as a condensed mode in the gasphase reactors.

Preferably, the process comprises also a prepolymerization with thecatalyst system, as described in detail below, comprising aZiegler-Natta procatalyst, an external donor and optionally acocatalyst.

In a preferred embodiment, the prepolymerization is conducted as bulkslurry polymerization in liquid propylene, i.e. the liquid phase mainlycomprises propylene, with minor amount of other reactants and optionallyinert components dissolved therein.

The prepolymerization reaction is typically conducted at a temperatureof 10 to 60° C., preferably from 15 to 50° C., and more preferably from20 to 45° C.

The pressure in the prepolymerization reactor is not critical but mustbe sufficiently high to maintain the reaction mixture in liquid phase.Thus, the pressure may be from 20 to 100 bar, for example 30 to 70 bar.

The catalyst components are preferably all introduced to theprepolymerization step. However, where the solid catalyst component (i)and the cocatalyst (ii) can be fed separately it is possible that only apart of the cocatalyst is introduced into the prepolymerization stageand the remaining part into subsequent polymerization stages. Also insuch cases it is necessary to introduce so much cocatalyst into theprepolymerization stage that a sufficient polymerization reaction isobtained therein.

It is possible to add other components also to the prepolymerizationstage. Thus, hydrogen may be added into the prepolymerization stage tocontrol the molecular weight of the prepolymer as is known in the art.Further, antistatic additive may be used to prevent the particles fromadhering to each other or to the walls of the reactor.

The precise control of the prepolymerization conditions and reactionparameters is within the skill of the art.

According to the invention the heterophasic propylene copolymer (RAHECO)is obtained by a multistage polymerization process, as described above,in the presence of a catalyst system.

As pointed out above in the specific process for the preparation of theheterophasic propylene copolymer (RAHECO) as defined above, a specificZiegler-Natta catalyst (ZN-C) must be used. Accordingly, theZiegler-Natta catalyst (ZN-C) will be now described in more detail.

The catalyst used in the present invention is a solid Ziegler-Nattacatalyst (ZN-C), which comprises compounds (TC) of a transition metal ofGroup 4 to 6 of IUPAC, like titanium, a Group 2 metal compound (MC),like a magnesium, and an internal donor (ID) being a non-phthaliccompound, preferably a non-phthalic acid ester, still more preferablybeing a diester of non-phthalic dicarboxylic acids as described in moredetail below. Thus, the catalyst is fully free of undesired phthaliccompounds. Further, the solid catalyst is free of any external supportmaterial, like silica or MgCl₂, but the catalyst is selfsupported.

The Ziegler-Natta catalyst (ZN-C) can be further defined by the way asobtained. Accordingly, the Ziegler-Natta catalyst (ZN-C) is preferablyobtained by a process comprising the steps of

-   a)    -   a₁) providing a solution of at least a Group 2 metal alkoxy        compound (Ax) being the reaction product of a Group 2 metal        compound (MC) and an alcohol (A) comprising in addition to the        hydroxyl moiety at least one ether moiety optionally in an        organic liquid reaction medium;    -   or    -   a₂) a solution of at least a Group 2 metal alkoxy compound (Ax′)        being the reaction product of a Group 2 metal compound (MC) and        an alcohol mixture of the alcohol (A) and a monohydric        alcohol (B) of formula ROH, optionally in an organic liquid        reaction medium;    -   or    -   a₃) providing a solution of a mixture of the Group 2 alkoxy        compound (Ax) and a Group 2 metal alkoxy compound (Bx) being the        reaction product of a Group 2 metal compound (MC) and the        monohydric alcohol (B), optionally in an organic liquid reaction        medium; and-   b) adding said solution from step a) to at least one compound (TC)    of a transition metal of Group 4 to 6 and-   c) obtaining the solid catalyst component particles,    and adding a non-phthalic internal electron donor (ID) at any step    prior to step c).

The internal donor (ID) or precursor thereof is added preferably to thesolution of step a).

According to the procedure above the Ziegler-Natta catalyst (ZN-C) canbe obtained via precipitation method or via emulsion (liquid/liquidtwo-phase system)—solidification method depending on the physicalconditions, especially temperature used in steps b) and c).

In both methods (precipitation or emulsion-solidification) the catalystchemistry is the same.

In precipitation method combination of the solution of step a) with atleast one transition metal compound (TC) in step b) is carried out andthe whole reaction mixture is kept at least at 50° C., more preferablyin the temperature range of 55 to 110° C., more preferably in the rangeof 70 to 100° C., to secure full precipitation of the catalyst componentin form of a solid particles (step c).

In emulsion—solidification method in step b) the solution of step a) istypically added to the at least one transition metal compound (TC) at alower temperature, such as from −10 to below 50° C., preferably from −5to 30° C. During agitation of the emulsion the temperature is typicallykept at −10 to below 40° C., preferably from −5 to 30° C. Droplets ofthe dispersed phase of the emulsion form the active catalystcomposition. Solidification (step c) of the droplets is suitably carriedout by heating the emulsion to a temperature of 70 to 150° C.,preferably to 80 to 110° C.

The catalyst prepared by emulsion—solidification method is preferablyused in the present invention.

In a preferred embodiment in step a) the solution of a₂) or a₃) areused, i.e. a solution of (Ax′) or a solution of a mixture of (Ax) and(Bx).

Preferably the Group 2 metal (MC) is magnesium.

The magnesium alkoxy compounds (Ax), (Ax′) and (Bx) can be prepared insitu in the first step of the catalyst preparation process, step a), byreacting the magnesium compound with the alcohol(s) as described above,or said magnesium alkoxy compounds can be separately prepared magnesiumalkoxy compounds or they can be even commercially available as readymagnesium alkoxy compounds and used as such in the catalyst preparationprocess of the invention.

Illustrative examples of alcohols (A) are monoethers of dihydricalcohols (glycol monoethers). Preferred alcohols (A) are C₂ to C₄ glycolmonoethers, wherein the ether moieties comprise from 2 to 18 carbonatoms, preferably from 4 to 12 carbon atoms. Preferred examples are2-(2-ethylhexyloxy)ethanol, 2-butyloxy ethanol, 2-hexyloxy ethanol and1,3-propylene-glycol-monobutyl ether, 3-butoxy-2-propanol, with2-(2-ethylhexyloxy)ethanol and 1,3-propylene-glycol-monobutyl ether,3-butoxy-2-propanol being particularly preferred.

Illustrative monohydric alcohols (B) are of formula ROH, with R beingstraight-chain or branched C₆-C₁₀ alkyl residue. The most preferredmonohydric alcohol is 2-ethyl-1-hexanol or octanol.

Preferably a mixture of Mg alkoxy compounds (Ax) and (Bx) or mixture ofalcohols (A) and (B), respectively, are used and employed in a moleratio of Bx:Ax or B:A from 8:1 to 2:1, more preferably 5:1 to 3:1.

Magnesium alkoxy compound may be a reaction product of alcohol(s), asdefined above, and a magnesium compound selected from dialkylmagnesiums, alkyl magnesium alkoxides, magnesium dialkoxides, alkoxymagnesium halides and alkyl magnesium halides. Alkyl groups can be asimilar or different C₁-C₂₀ alkyl, preferably C₂-C₁₀ alkyl. Typicalalkyl-alkoxy magnesium compounds, when used, are ethyl magnesiumbutoxide, butyl magnesium pentoxide, octyl magnesium butoxide and octylmagnesium octoxide. Preferably the dialkyl magnesiums are used. Mostpreferred dialkyl magnesiums are butyl octyl magnesium or butyl ethylmagnesium.

It is also possible that magnesium compound can react in addition to thealcohol (A) and alcohol (B) also with a polyhydric alcohol (C) offormula R″ (OH)_(m) to obtain said magnesium alkoxide compounds.Preferred polyhydric alcohols, if used, are alcohols, wherein R″ is astraight-chain, cyclic or branched C₂ to C₁₀ hydrocarbon residue, and mis an integer of 2 to 6.

The magnesium alkoxy compounds of step a) are thus selected from thegroup consisting of magnesium dialkoxides, diaryloxy magnesiums,alkyloxy magnesium halides, aryloxy magnesium halides, alkyl magnesiumalkoxides, aryl magnesium alkoxides and alkyl magnesium aryloxides. Inaddition a mixture of magnesium dihalide and a magnesium dialkoxide canbe used.

The solvents to be employed for the preparation of the present catalystmay be selected among aromatic and aliphatic straight chain, branchedand cyclic hydrocarbons with 5 to 20 carbon atoms, more preferably 5 to12 carbon atoms, or mixtures thereof. Suitable solvents include benzene,toluene, cumene, xylene, pentane, hexane, heptane, octane and nonane.Hexanes and pentanes are particular preferred.

Mg compound is typically provided as a 10 to 50 wt-% solution in asolvent as indicated above. Typical commercially available Mg compound,especially dialkyl magnesium solutions are 20-40 wt-% solutions intoluene or heptanes.

The reaction for the preparation of the magnesium alkoxy compound may becarried out at a temperature of 40° to 70° C. Most suitable temperatureis selected depending on the Mg compound and alcohol(s) used.

The transition metal compound of Group 4 to 6 is preferably a titaniumcompound, most preferably a titanium halide, like TiCl₄.

The internal donor (ID) used in the preparation of the catalyst used inthe present invention is preferably selected from (di)esters ofnon-phthalic carboxylic (di)acids, 1,3-diethers, derivatives andmixtures thereof. Especially preferred donors are diesters ofmono-unsaturated dicarboxylic acids, in particular esters belonging to agroup comprising malonates, maleates, succinates, citraconates,glutarates, cyclohexene-1,2-dicarboxylates and benzoates, and anyderivatives and/or mixtures thereof. Preferred examples are e.g.substituted maleates and citraconates, most preferably citraconates.

In emulsion method, the two phase liquid-liquid system may be formed bysimple stirring and optionally adding (further) solvent(s) andadditives, such as the turbulence minimizing agent (TMA) and/or theemulsifying agents and/or emulsion stabilizers, like surfactants, whichare used in a manner known in the art for facilitating the formation ofand/or stabilize the emulsion. Preferably, surfactants are acrylic ormethacrylic polymers. Particular preferred are unbranched C₁₂ to C₂₀(meth)acrylates such as poly(hexadecyl)-methacrylate andpoly(octadecyl)-methacrylate and mixtures thereof. Turbulence minimizingagent (TMA), if used, is preferably selected from α-olefin polymers ofα-olefin monomers with 6 to 20 carbon atoms, like polyoctene,polynonene, polydecene, polyundecene or polydodecene or mixturesthereof. Most preferable it is polydecene.

The solid particulate product obtained by precipitation oremulsion—solidification method may be washed at least once, preferablyat least twice, most preferably at least three times with a aromaticand/or aliphatic hydrocarbons, preferably with toluene, heptane orpentane. The catalyst can further be dried, as by evaporation orflushing with nitrogen, or it can be slurried to an oily liquid withoutany drying step.

The finally obtained Ziegler-Natta catalyst is desirably in the form ofparticles having generally an average particle size range of 5 to 200μm, preferably 10 to 100. Particles are compact with low porosity andhave surface area below 20 g/m², more preferably below 10 g/m².Typically the amount of Ti is 1 to 6 wt-%, Mg 10 to 20 wt-% and donor 10to 40 wt-% of the catalyst composition.

Detailed description of preparation of catalysts is disclosed in WO2012/007430, EP2610271, EP 261027 and EP2610272 which are incorporatedhere by reference.

The Ziegler-Natta catalyst (ZN-C) is preferably used in association withan alkyl aluminum cocatalyst and optionally external donors.

As further component in the instant polymerization process an externaldonor (ED) is preferably present. Suitable external donors (ED) includecertain silanes, ethers, esters, amines, ketones, heterocyclic compoundsand blends of these. It is especially preferred to use a silane. It ismost preferred to use silanes of the general formula

R^(a) _(p)R^(b) _(q)Si(OR^(c))_((4-p-q))

wherein R^(a), R^(b) and R^(c) denote a hydrocarbon radical, inparticular an alkyl or cycloalkyl group, and wherein p and q are numbersranging from 0 to 3 with their sum p+q being equal to or less than 3.R^(a), R^(b) and R^(c) can be chosen independently from one another andcan be the same or different. Specific examples of such silanes are(tert-butyl)₂Si(OCH₃)₂, (cyclohexyl)(methyl)Si(OCH₃)²,(phenyl)₂Si(OCH₃)₂ and (cyclopentyl)₂Si(OCH₃)₂, or of general formula

Si(OCH₂CH₃)₃(NR³R⁴)

wherein R³ and R⁴ can be the same or different a represent a hydrocarbongroup having 1 to 12 carbon atoms.

R³ and R⁴ are independently selected from the group consisting of linearaliphatic hydrocarbon group having 1 to 12 carbon atoms, branchedaliphatic hydrocarbon group having 1 to 12 carbon atoms and cyclicaliphatic hydrocarbon group having 1 to 12 carbon atoms. It is inparticular preferred that R³ and R⁴ are independently selected from thegroup consisting of methyl, ethyl, n-propyl, n-butyl, octyl, decanyl,iso-propyl, iso-butyl, iso-pentyl, tert.-butyl, tert.-amyl, neopentyl,cyclopentyl, cyclohexyl, methylcyclopentyl and cycloheptyl.

More preferably both R¹ and R² are the same, yet more preferably both R³and R⁴ are an ethyl group.

Especially preferred external donors (ED) are the pentyl dimethoxysilane donor (D-donor) or the cyclohexylmethyl dimethoxy silane donor(C-Donor), the latter especially preferred.

In addition to the Ziegler-Natta catalyst (ZN-C) and the optionalexternal donor (ED) a co-catalyst can be used. The co-catalyst ispreferably a compound of group 13 of the periodic table (IUPAC), e.g.organo aluminum, such as an aluminum compound, like aluminum alkyl,aluminum halide or aluminum alkyl halide compound. Accordingly, in onespecific embodiment the co-catalyst (Co) is a trialkylaluminum, liketriethylaluminium (TEAL), dialkyl aluminium chloride or alkyl aluminiumdichloride or mixtures thereof. In one specific embodiment theco-catalyst (Co) is triethylaluminium (TEAL).

Advantageously, the triethyl aluminium (TEAL) has a hydride content,expressed as AlH₃, of less than 1.0 wt % with respect to the triethylaluminium (TEAL). More preferably, the hydride content is less than 0.5wt %, and most preferably the hydride content is less than 0.1 wt %.

Preferably the ratio between the co-catalyst (Co) and the external donor(ED) [Co/ED] and/or the ratio between the co-catalyst (Co) and thetransition metal (TM) [Co/TM] should be carefully chosen.

Accordingly,

(a) the mol-ratio of co-catalyst (Co) to external donor (ED) [Co/ED]must be in the range of 5 to 45, preferably is in the range of 5 to 35,more preferably is in the range of 5 to 25; and optionally(b) the mol-ratio of co-catalyst (Co) to titanium compound (TC) [Co/TC]must be in the range of above 80 to 500, preferably is in the range of100 to 450, still more preferably is in the range of 120 to 350.

In the following the present invention is further illustrated by meansof examples.

EXAMPLES 1. Measuring Methods

The following definitions of terms and determination methods apply forthe above general description of the invention as well as to the belowexamples unless otherwise defined. Calculation of comonomer content ofthe second propylene copolymer fraction (R-PP2):

$\begin{matrix}{\frac{{C({PP})} - {{w\left( {{PP}\; 1} \right)} \times {C\left( {{PP}\; 1} \right)}}}{w\left( {{PP}\; 2} \right)} = {C\left( {{PP}\; 2} \right)}} & (I)\end{matrix}$

wherein

-   w(PP1) is the weight fraction [in wt.-%] of the first propylene    copolymer fraction (R-PP1),-   w(PP2) is the weight fraction [in wt.-%] of second propylene    copolymer fraction (R-PP2),-   C(PP1) is the comonomer content [in mol-%] of the first propylene    copolymer fraction (R-PP1),-   C(PP) is the comonomer content [in mol-%] of the random propylene    copolymer (R-PP),-   C(PP2) is the calculated comonomer content [in mol-%] of the second    propylene copolymer fraction (R-PP2).

Calculation of the xylene cold soluble (XCS) content of the secondpropylene copolymer fraction (R-PP2):

$\begin{matrix}{\frac{{{XS}({PP})} - {{w\left( {{PP}\; 1} \right)} \times {{XS}\left( {{PP}\; 1} \right)}}}{w\left( {{PP}\; 2} \right)} = {{XS}\left( {{PP}\; 2} \right)}} & ({II})\end{matrix}$

wherein

-   w(PP1) is the weight fraction [in wt.-%] of the first propylene    copolymer fraction (R-PP1),-   w(PP2) is the weight fraction [in wt.-%] of second propylene    copolymer fraction (R-PP2),-   XS(PP1) is the xylene cold soluble (XCS) content [in wt.-%] of the    first propylene copolymer fraction (R-PP1),-   XS(PP) is the xylene cold soluble (XCS) content [in wt.-%] of the    random propylene copolymer (R-PP),-   XS(PP2) is the calculated xylene cold soluble (XCS) content [in    wt.-%] of the second propylene copolymer fraction (R-PP2),    respectively.

Calculation of melt flow rate MFR₂ (230° C.) of the second propylenecopolymer fraction (R-PP2):

$\begin{matrix}{{{MFR}\left( {{PP}\; 2} \right)} = 10^{\lbrack\frac{{\log {({{MFR}{({PP})}})}} - {{w{({{PP}\; 1})}} \times {\log {({{MFR}{({{PP}\; 1})}})}}}}{w{({{PP}\; 2})}}\rbrack}} & ({III})\end{matrix}$

wherein

-   w(PP1) is the weight fraction [in wt.-%] of the first propylene    copolymer fraction (R-PP1),-   w(PP2) is the weight fraction [in wt.-%] of second propylene    copolymer fraction (R-PP2),-   MFR(PP1) is the melt flow rate MFR₂ (230° C.) [in g/10 min] of the    first propylene copolymer fraction (R-PP1),-   MFR(PP) is the melt flow rate MFR₂ (230° C.) [in g/10 min] of the    random propylene copolymer (R-PP),-   MFR(PP2) is the calculated melt flow rate MFR₂ (230° C.) [in g/10    min] of the second propylene copolymer fraction (R-PP2).

Calculation of comonomer content of the elastomeric propylene copolymer(E), respectively:

$\begin{matrix}{\frac{{C({RAHECO})} - {{w({PP}\;)} \times {C({PP}\;)}}}{w(E)} = {C(E)}} & ({IV})\end{matrix}$

wherein

-   w(PP) is the weight fraction [in wt.-%] of the random propylene    copolymer (R-PP), i.e. polymer produced in the first and second    reactor (R1+R2),-   w(E) is the weight fraction [in wt.-%] of the elastomeric propylene    copolymer (E), i.e. polymer produced in the third and fourth reactor    (R3+R4)-   C(PP) is the comonomer content [in mol-%] of the random propylene    copolymer (R-PP), i.e. comonomer content [in wt.-%] of the polymer    produced in the first and second reactor (R1+R2),-   C(RAHECO) is the comonomer content [in mol-%] of the propylene    copolymer, i.e. is the comonomer content [in mol-%] of the polymer    obtained after polymerization in the fourth reactor (R4),-   C(E) is the calculated comonomer content [in mol-%] of elastomeric    propylene copolymer (E), i.e. of the polymer produced in the third    and fourth reactor (R3+R4).

MFR₂ (230° C.) is measured according to ISO 1133 (230° C., 2.16 kgload).

Quantification of Microstructure by NMR Spectroscopy

Quantitative nuclear-magnetic resonance (NMR) spectroscopy was used toquantify the comonomer content and comonomer sequence distribution ofthe polymers. Quantitative ¹³C {¹H} NMR spectra were recorded in thesolution-state using a Bruker Advance III 400 NMR spectrometer operatingat 400.15 and 100.62 MHz for ¹H and ¹³C respectively. All spectra wererecorded using a ¹³C optimised 10 mm extended temperature probehead at125° C. using nitrogen gas for all pneumatics. Approximately 200 mg ofmaterial was dissolved in 3 ml of 1,2-tetrachloroethane-d₂ (TCE-d₂)along with chromium-(III)-acetylacetonate (Cr(acac)₃) resulting in a 65mM solution of relaxation agent in solvent (Singh, G., Kothari, A.,Gupta, V., Polymer Testing 28 5 (2009), 475). To ensure a homogenoussolution, after initial sample preparation in a heat block, the NMR tubewas further heated in a rotatary oven for at least 1 hour. Uponinsertion into the magnet the tube was spun at 10 Hz. This setup waschosen primarily for the high resolution and quantitatively needed foraccurate ethylene content quantification. Standard single-pulseexcitation was employed without NOE, using an optimised tip angle, 1 srecycle delay and a bi-level WALTZ16 decoupling scheme (Zhou, Z.,Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha, A., Baugh, D.Winniford, B., J. Mag. Reson. 187 (2007) 225; Busico, V., Carbonniere,P., Cipullo, R., Pellecchia, R., Severn, J., Talarico, G., Macromol.Rapid Commun. 2007, 28, 1128). A total of 6144 (6 k) transients wereacquired per spectra. Quantitative ¹³C {¹H} NMR spectra were processed,integrated and relevant quantitative properties determined from theintegrals using proprietary computer programs. All chemical shifts wereindirectly referenced to the central methylene group of the ethyleneblock (EEE) at 30.00 ppm using the chemical shift of the solvent. Thisapproach allowed comparable referencing even when this structural unitwas not present. Characteristic signals corresponding to theincorporation of ethylene were observed Cheng, H. N., Macromolecules 17(1984), 1950).

With characteristic signals corresponding to 2,1 erythro regio defectsobserved (as described in L. Resconi, L. Cavallo, A. Fait, F.Piemontesi, Chem. Rev. 2000, 100 (4), 1253, in Cheng, H. N.,Macromolecules 1984, 17, 1950, and in W-J. Wang and S. Zhu,Macromolecules 2000, 33 1157) the correction for the influence of theregio defects on determined properties was required. Characteristicsignals corresponding to other types of regio defects were not observed.

The comonomer fraction was quantified using the method of Wang et. al.(Wang, W-J., Zhu, S., Macromolecules 33 (2000), 1157) throughintegration of multiple signals across the whole spectral region in the¹³C {¹H} spectra. This method was chosen for its robust nature andability to account for the presence of regio-defects when needed.Integral regions were slightly adjusted to increase applicability acrossthe whole range of encountered comonomer contents.

For systems where only isolated ethylene in PPEPP sequences was observedthe method of Wang et. al. was modified to reduce the influence ofnon-zero integrals of sites that are known to not be present. Thisapproach reduced the overestimation of ethylene content for such systemsand was achieved by reduction of the number of sites used to determinethe absolute ethylene content to:

E=0.5(Sββ+Sβγ+Sβδ+0.5(Sαβ+Sαγ))

Through the use of this set of sites the corresponding integral equationbecomes:

E=0.5(I _(H) +I _(G)+0.5(I _(c) +I _(D)))

using the same notation used in the article of Wang et. al. (Wang, W-J.,Zhu, S., Macromolecules 33 (2000), 1157). Equations used for absolutepropylene content were not modified.

The mole percent comonomer incorporation was calculated from the molefraction:

E [mol %]=100*fE

The weight percent comonomer incorporation was calculated from the molefraction:

E [wt %]=100*(fE*28.06)/((fE*28.06)+((1−fE)*42.08))

The comonomer sequence distribution at the triad level was determinedusing the analysis method of Kakugo et al. (Kakugo, M., Naito, Y.,Mizunuma, K., Miyatake, T. Macromolecules 15 (1982) 1150). This methodwas chosen for its robust nature and integration regions slightlyadjusted to increase applicability to a wider range of comonomercontents.

The relative content of isolated to block ethylene incorporation wascalculated from the triad sequence distribution using the followingrelationship (equation (I)):

$\begin{matrix}{{I(E)} = {\frac{fPEP}{\left( {{fEEE} + {fPEE} + {fPEP}} \right)} \times 100}} & (I)\end{matrix}$

whereinI(E) is the relative content of isolated to block ethylene sequences [in%];fPEP is the mol fraction of propylene/ethylene/propylene sequences (PEP)in the sample;fPEE is the mol fraction of propylene/ethylene/ethylene sequences (PEE)and of ethylene/ethylene/propylene sequences (EEP) in the sample;fEEE is the mol fraction of ethylene/ethylene/ethylene sequences (EEE)in the sample

Intrinsic viscosity is measured according to DIN ISO 1628/1, October1999 (in Decalin at 135° C.).

The xylene solubles (XCS, wt.-%): Content of xylene cold solubles (XCS)is determined at 25° C. according ISO 16152; first edition; 2005-07-01.The part which remains insoluble is the xylene cold insoluble (XCI)fraction.

Melting temperature (T_(m)) and heat of fusion (H_(f)), crystallizationtemperature (T_(c)) and heat of crystallization (H_(c)): measured withMettler TA820 differential scanning calorimetry (DSC) on 5 to 10 mgsamples. DSC is run according to ISO 11357-3:1999 in a heat/cool/heatcycle with a scan rate of 10° C./min in the temperature range of +23 to+210° C. Crystallization temperature and heat of crystallization (H_(c))are determined from the cooling step, while melting temperature and heatof fusion (H_(f)) are determined from the second heating step.

The glass transition temperature Tg is determined by dynamic mechanicalanalysis according to ISO 6721-7. The measurements are done in torsionmode on compression moulded samples (40×10×1 mm³) between −100° C. and+150° C. with a heating rate of 2° C./min and a frequency of 1 Hz.

Transparency, haze and clarity were determined according to ASTMD1003-00 on 60×60×1 mm³ plaques injection molded in line with EN ISO1873-2 using a melt temperature of 200° C.

Flexural Modulus: The flexural modulus was determined in 3-point-bendingaccording to ISO 178 on 80×10×4 mm³ test bars injection molded at 23° C.in line with EN ISO 1873-2.

Charpy notched impact strength is determined according to ISO 179 1eA at23°, and at −20° C. by using an 80×10×4 mm³ test bars injection moldedin line with EN ISO 1873-2.

2. Examples

The catalyst used in the polymerization processes for the heterophasicpropylene copolymers (RAHECO) of the inventive examples (IE) wasprepared as follows:

Used Chemicals:

20% solution in toluene of butyl ethyl magnesium (Mg(Bu)(Et), BEM),provided by Chemtura2-ethylhexanol, provided by Amphochem3-Butoxy-2-propanol—(DOWANOL™ PnB), provided by Dowbis(2-ethylhexyl)citraconate, provided by SynphaBaseTiCl₄, provided by Millenium ChemicalsToluene, provided by AspokemViscoplex® 1-254, provided by EvonikHeptane, provided by Chevron

Preparation of a Mg Alkoxy Compound

Mg alkoxide solution was prepared by adding, with stirring (70 rpm),into 11 kg of a 20 wt-% solution in toluene of butyl ethyl magnesium(Mg(Bu)(Et)), a mixture of 4.7 kg of 2-ethylhexanol and 1.2 kg ofbutoxypropanol in a 20 l stainless steel reactor. During the additionthe reactor contents were maintained below 45° C. After addition wascompleted, mixing (70 rpm) of the reaction mixture was continued at 60°C. for 30 minutes. After cooling to room temperature 2.3 kg g of thedonor bis(2-ethylhexyl)citraconate was added to the Mg-alkoxide solutionkeeping temperature below 25° C. Mixing was continued for 15 minutesunder stirring (70 rpm).

Preparation of Solid Catalyst Component

20.3 kg of TiCl₄ and 1.1 kg of toluene were added into a 20 l stainlesssteel reactor. Under 350 rpm mixing and keeping the temperature at 0°C., 14.5 kg of the Mg alkoxy compound prepared in example 1 was addedduring 1.5 hours. 1.7 l of Viscoplex® 1-254 and 7.5 kg of heptane wereadded and after 1 hour mixing at 0° C. the temperature of the formedemulsion was raised to 90° C. within 1 hour. After 30 minutes mixing wasstopped catalyst droplets were solidified and the formed catalystparticles were allowed to settle. After settling (1 hour), thesupernatant liquid was siphoned away. Then the catalyst particles werewashed with 45 kg of toluene at 90° C. for 20 minutes followed by twoheptane washes (30 kg, 15 min) During the first heptane wash thetemperature was decreased to 50° C. and during the second wash to roomtemperature.

The thus obtained catalyst was used along with triethyl-aluminium (TEAL)as co-catalyst and dicyclopentyl dimethoxy silane (D-Donor) as donor.

The aluminium to donor ratio, the aluminium to titanium ratio and thepolymerization conditions are indicated in table 1.

Comparative example 1 is the commercial grade Borsoft SA233CF producedby Borealis being an ethylene-propylene random-heterophasic copolymer.Comparative example 2 is the commercial grade Borsoft SC820CF producedby Borealis being an ethylene-propylene random-heterophasic copolymer.

TABLE 1 Polymerization conditions IE 1 IE 4 IE 7 PrepolymerizationTEAL/Ti [mol/mol] 280 280 220 TEAL/donor [mol/mol] 7.5 7.5 6.1Temperature [° C.] 30 30 20 C2 feed [kg/h] 0.33 0.33 0.33 res. time [h]0.36 0.36 0.37 Loop Temperature [° C.] 70 70 70 Split [%] 37 36 17 H2/C3ratio [mol/kmol] 0.23 0.23 0.7 C2/C3 ratio [mol/kmol] 4.31 4.1 5.3 MFR₂[g/10 min] 0.68 0.61 4.4 XCS [wt.-%] 6.2 6.0 6.3 C2 content [mol-%] 3.63.4 4.0 GPR 1 Temperature [° C.] 80 80 80 Pressure [kPa] 2200 2200 2000Split [%] 47 47 63 H2/C3 ratio [mol/kmol] 36 120 151 C2/C3 ratio[mol/kmol] 576 573 494 MFR₂ [g/10 min] 0.65 0.72 4.6 XCS [wt.-%] 7.3 9.39.0 C2 content [mol-%] 6.6 8.6 6.9 GPR 2 Temperature [° C.] 70 70 75Pressure [kPa] 1600 1600 2500 Split [%] 16 17 20 C2/C3 ratio [mol/kmol]36 120 151 H2/C2 ratio [mol/kmol] 576 573 494 MFR₂ [g/10 min] 0.54 0.662.8 XCS [wt.-%] 22.0 22.4 27.1 C2 content [mol-%] 17.3 16.0 17.7 C2ethylene H₂/C3 ratio hydrogen/propylene ratio C2/C3 ratioethylene/propylene ratio 1/2/3 GPR 1/2/3 gas phase reactor Loop Loopreactor

TABLE 2 Properties IE1 IE2 IE3 IE4 IE5 IE6 IE8 CE1 CE2 MFR₂ [g/10 min]0.54 3.94 12.7 0.66 3.75 12.9 12.36 0.5 4.6 VR [−] 0 6 23 0 5 19 3 0 0C2 (total) [mol-%] 17.3 17.3 17.3 16.0 16.0 16.0 17.7 14.6 12.0 XCS[wt.-%] 22.0 21.5 21.2 22.4 22.0 21.8 26.6 21.8 19.4 C2 (XCS) [mol-%]45.7 45.5 45.4 39.1 38.5 38.2 42.1 40.6 39.1 iV (XCS) [dl/g] 4.1 3.8 3.13.0 2.8 2.0 2.6 2.7 1.6 Tc [° C.] 106 106 106 105.6 105.6 105.6 102.995.8 103.2 Tm [° C.] 144.8 144.8 144.8 144.1 144.1 144.1 142.5 139.5141.3 Tg (2) [° C.] −55.0 −55.4 −55.0 −54.7 −54.8 −54.5 −54.7 −54.0−54.1 Tg (1) [° C.] −4.3 −5.1 −4.8 −6.1 −6.4 −7.1 −3.7 −4.0 −4.1 NIS @23° C. [kJ/m²] 86.9 35.5 16.9 82.4 42.5 20.6 13.78 72 11.4 NIS @ −20° C.[kJ/m²] 6.0 5.3 4.7 3.2 3.6 3.6 3.83 2 1.1 FM [Mpa] 545 524 511 458 452447 495 514 576 Haze [%] 100 97 97 93 85 86 93 75 60 VR visbreakingratio C2 ethylene Tg(1) glass transition temperature of the matrix (M)Tg(2) glass transition temperature of the elastomeric propylenecopolymer (E) FM Flexural modulus

TABLE 3 Relative content of isolated to block ethylene sequences (I(E))of the XCI fraction IE 1 IE 4 IE 7 CE 1 I(E)¹⁾ [%] 56.9 57.6 57.6 66.7fEEE [mol.-%] 1.67 1.53 1.63 1.05 fEEP [mol.-%] 1.22 1.07 0.98 0.85 fPEP[mol.-%] 3.81 3.53 3.54 3.8${\,^{1)}{IE}} = {\frac{fPEP}{\left( {{fEEE} + {fPEE} + {fPEP}} \right)} \times 100}$

The inventive heterophasic propylene copolymers (RAHECO) IE2 and IE3(based on IE1), IE5 and IE6 (based on IE4), and IE7 (based on the 3^(rd)reactor product from Table 1) have been visbroken by using a co-rotatingtwin-screw extruder at 200-230° C. and using an appropriate amount of(tert.-butylperoxy)-2,5-dimethylhexane (Trigonox 101, distributed byAkzo Nobel, Netherlands) to achieve the target MFR₂ as mentioned intable 1. All products were stabilized with 0.2 wt.-% of Irganox B225(1:1-blend of Irganox 1010(Pentaerythrityl-tetrakis(3-(3′,5′-di-tert.butyl-4-hydroxytoluyl)-propionateand tris (2,4-di-t-butylphenyl) phosphate) phosphite) of BASF AG,Germany) and 0.1 wt.-% calcium stearate.

As can be gathered from Table 1, the inventive examples show anoptimized or improved balance between stiffness and toughness. Further,FIG. 1 shows that the inventive examples show an improved toughness asfunction of processability.

1-20. (canceled)
 21. A heterophasic propylene copolymer (RAHECO), saidheterophasic propylene copolymer (RAHECO) comprises a matrix (M) being arandom propylene copolymer (R-PP) and an elastomeric propylene copolymer(E) dispersed in said matrix (M), wherein the heterophasic propylenecopolymer (RAHECO) has a) a melt flow rate MFR₂ (230° C.) measuredaccording to ISO 1133 in the range of 0.3 to 20.0 g/10 min, b) a xylenecold soluble content (XCS) determined according ISO 16152 (25° C.) inthe range of 16.0 to 50.0 wt.-%, c) a comonomer content in the range of11.5 to 21.0 mol-%, and wherein further the heterophasic propylenecopolymer (RAHECO) has a Charpy notched impact strength as defined byin-equation (III)NIS>60−23.0×In(MFR)  (III) wherein “NIS” is the Charpy notched impactstrength according to ISO 179-1eA:2000 at 23° C. [in kJ/m²] of theheterophasic propylene copolymer (RAHECO), and “MFR” is the MFR₂ (230°C./2.16 kg) [in g/10 min] of the heterophasic propylene copolymer(RAHECO), wherein further d) the xylene cold insoluble fraction (XCI) ofthe heterophasic propylene copolymer (RAHECO) has a relative content ofisolated to block ethylene sequences (I(E)) in the range of 50.0 to65.0%, wherein the I(E) content is defined by equation (I)$\begin{matrix}{{I(E)} = {\frac{fPEP}{\left( {{fEEE} + {fPEE} + {fPEP}} \right)} \times 100}} & (I)\end{matrix}$ wherein I(E) is the relative content of isolated to blockethylene sequences [in %]; fPEP is the mol fraction ofpropylene/ethylene/propylene sequences (PEP) in the xylene coldinsoluble fraction (XCI) of the heterophasic propylene copolymer(RAHECO); fPEE is the mol fraction of propylene/ethylene/ethylenesequences (PEE) and of ethylene/ethylene/propylene sequences (EEP) inthe xylene cold insoluble fraction (XCI) of the heterophasic propylenecopolymer (RAHECO); fEEE is the mol fraction ofethylene/ethylene/ethylene sequences (EEE) in the xylene cold insolublefraction (XCI) of the heterophasic propylene copolymer (RAHECO), whereinall sequence concentrations being based on a statistical triad analysisof ¹³C-NMR data.
 22. The heterophasic propylene copolymer (RAHECO)according to claim 21, wherein the heterophasic propylene copolymer(RAHECO) is free of phthalic acid esters as well as their respectivedecomposition products.
 23. A heterophasic propylene copolymer (RAHECO),said heterophasic propylene copolymer (RAHECO) comprises a matrix (M)being a random propylene copolymer (R-PP) and an elastomeric propylenecopolymer (E) dispersed in said matrix (M), wherein the heterophasicpropylene copolymer (RAHECO) has a) a melt flow rate MFR₂ (230° C.)measured according to ISO 1133 in the range of 0.3 to 20.0 g/10 min, b)a xylene cold soluble content (XCS) determined according ISO 16152 (25°C.) in the range of 16.0 to 50.0 wt.-%, c) a comonomer content in therange of 11.5 to 21.0 mol-%, and wherein further the heterophasicpropylene copolymer (RAHECO) has a Charpy notched impact strength asdefined by in-equation (III)NIS>60−23.0×In(MFR)  (III) wherein “NIS” is the Charpy notched impactstrength according to ISO 179-1eA:2000 at 23° C. [in kJ/m²] of theheterophasic propylene copolymer (RAHECO), and “MFR” is the MFR₂ (230°C./2.16 kg) [in g/10 min] of the heterophasic propylene copolymer(RAHECO).
 24. The heterophasic propylene copolymer (RAHECO) according toclaim 23, wherein a) the xylene cold insoluble fraction (XCI) of theheterophasic propylene copolymer (RAHECO) has a relative content ofisolated to block ethylene sequences (I(E)) in the range of 50.0 to65.0%, wherein the I(E) content is defined by equation (I)$\begin{matrix}{{I(E)} = {\frac{fPEP}{\left( {{fEEE} + {fPEE} + {fPEP}} \right)} \times 100}} & (I)\end{matrix}$ wherein I(E) is the relative content of isolated to blockethylene sequences [in %]; fPEP is the mol fraction ofpropylene/ethylene/propylene sequences (PEP) in the xylene coldinsoluble fraction (XCI) of the heterophasic propylene copolymer(RAHECO); fPEE is the mol fraction of propylene/ethylene/ethylenesequences (PEE) and of ethylene/ethylene/propylene sequences (EEP) inthe xylene cold insoluble fraction (XCI) of the heterophasic propylenecopolymer (RAHECO); fEEE is the mol fraction ofethylene/ethylene/ethylene sequences (EEE) in the xylene cold insolublefraction (XCI) of the heterophasic propylene copolymer (RAHECO), whereinall sequence concentrations being based on a statistical triad analysisof ¹³C-NMR data and/or b) wherein the heterophasic propylene copolymer(RAHECO) is free of phthalic acid esters as well as their respectivedecomposition products.
 25. A heterophasic propylene copolymer (RAHECO),said heterophasic propylene copolymer (RAHECO) comprises a matrix (M)being a random propylene copolymer (R-PP) and an elastomeric propylenecopolymer (E) dispersed in said matrix (M), wherein the heterophasicpropylene copolymer (RAHECO) has a) a melt flow rate MFR₂ (230° C.)measured according to ISO 1133 in the range of 0.3 to 20.0 g/10 min, b)a xylene cold soluble content (XCS) determined according ISO 16152 (25°C.) in the range of 16.0 to 50.0 wt.-%, and c) a comonomer content inthe range of 11.5 to 21.0 mol-%, wherein further the heterophasicpropylene copolymer (RAHECO) is free of phthalic acid esters as well astheir respective decomposition products.
 26. Heterophasic propylenecopolymer (RAHECO) according to claim 25, wherein the xylene coldinsoluble fraction (XCI) of the heterophasic propylene copolymer(RAHECO) has a relative content of isolated to block ethylene sequences(I(E)) in the range of 50.0 to 65.0%, wherein the I(E) content isdefined by equation (I) $\begin{matrix}{{I(E)} = {\frac{fPEP}{\left( {{fEEE} + {fPEE} + {fPEP}} \right)} \times 100}} & (I)\end{matrix}$ wherein I(E) is the relative content of isolated to blockethylene sequences [in %]; fPEP is the mol fraction ofpropylene/ethylene/propylene sequences (PEP) in the xylene coldinsoluble fraction (XCI) of the heterophasic propylene copolymer(RAHECO); fPEE is the mol fraction of propylene/ethylene/ethylenesequences (PEE) and of ethylene/ethylene/propylene sequences (EEP) inthe xylene cold insoluble fraction (XCI) of the heterophasic propylenecopolymer (RAHECO); fEEE is the mol fraction ofethylene/ethylene/ethylene sequences (EEE) in the xylene cold insolublefraction (XCI) of the heterophasic propylene copolymer (RAHECO), whereinall sequence concentrations being based on a statistical triad analysisof ¹³C-NMR data.
 27. The heterophasic propylene copolymer (RAHECO)according to claim 21, wherein the xylene cold soluble content (XCS) hasi) a comonomer content in the range of 36.5 to 50.0 mol-%, and/or ii) anintrinsic viscosity (IV) determined according to DIN ISO 1628/1, (inDecalin at 135° C.) in the range of 2.0 to 4.5 dl/g.
 28. Theheterophasic propylene copolymer (RAHECO) according to claim 21, whereinthe random propylene copolymer (R-PP) has i) before vis-breaking a meltflow rate MFR₂ (230° C.) measured according to ISO 1133 in the range of3.0 to 8.0 g/10 min, and/or ii) a comonomer content in the range of 4.4to 9.0 mol-%.
 29. The heterophasic propylene copolymer (RAHECO)according to claim 21, wherein the comonomers of the random propylenecopolymer (R-PP) and/or the comonomers of the elastomeric propylenecopolymer (E) are ethylene and/or C₄ to C₈ α-olefin.
 30. Theheterophasic propylene copolymer (RAHECO) according to claim 21, whereinthe heterophasic propylene copolymer (RAHECO) comprises 60.0 to 90.0wt.-%, based on the total weight of the heterophasic propylene copolymer(RAHECO), of the random propylene copolymer (R-PP) and 10.0 to 40.0wt.-%, based on the total weight of the heterophasic propylene copolymer(RAHECO), of the elastomeric propylene copolymer (E).
 31. Theheterophasic propylene copolymer (RAHECO) according to claim 21, whereinthe heterophasic propylene copolymer (RAHECO) has been visbroken. 32.The heterophasic propylene copolymer (RAHECO) according to claim 31,wherein the heterophasic propylene copolymer (RAHECO) has been visbrokenwith a visbreaking ratio (VR) as defined by in-equation (II)$\begin{matrix}{1.5 \leq \frac{{MFRfinal} - {MFRinitial}}{MFRinitial} \leq 30.0} & ({II})\end{matrix}$ wherein “MFRfinal” is the MFR₂ (230° C./2.16 kg) of theheterophasic propylene copolymer (RAHECO) after visbreaking and“MFRinitial” is the MFR₂ (230° C./2.16 kg) of the heterophasic propylenecopolymer (RAHECO) before visbreaking
 33. The heterophasic propylenecopolymer (RAHECO) according to claim 21, wherein the heterophasicpropylene copolymer (RAHECO) has been polymerized in the presence of a)a Ziegler-Natta catalyst (ZN-C) comprising compounds (TC) of atransition metal of Group 4 to 6 of IUPAC, a Group 2 metal compound (MC)and an internal donor (ID), wherein said internal donor (ID) is anon-phthalic compound; b) optionally a co-catalyst (Co), and c)optionally an external donor (ED).
 34. The heterophasic propylenecopolymer (RAHECO) according to claim 33, wherein a) the internal donor(ID) is selected from optionally substituted malonates, maleates,succinates, glutarates, cyclohexene-1,2-dicarboxylates, benzoates andderivatives and/or mixtures thereof; b) the molar-ratio of co-catalyst(Co) to external donor (ED) [Co/ED] is 5 to
 45. 35. The heterophasicpropylene copolymer (RAHECO) according to claim 21, wherein theheterophasic propylene copolymer (RAHECO) comprising a matrix (M) beinga random propylene copolymer (R-PP) and an elastomeric propylenecopolymer (E) dispersed in said matrix (M) is produced in a multistageprocess comprising at least two reactors connected in series.
 36. Theheterophasic propylene copolymer (RAHECO) according to claim 35, wherein(a) in a first reactor propylene and ethylene and/or C₄ to C₈ α-olefinare polymerized obtaining a first propylene copolymer fraction (PP1),(b) transferring said first propylene copolymer fraction (PP1) in asecond reactor, (c) polymerizing in said second reactor in the presenceof the first propylene copolymer fraction (PP1) propylene and ethyleneand/or C₄ to C₈ α-olefin obtaining a second propylene copolymer fraction(PP2), said first propylene copolymer fraction (PP1) and said secondpropylene copolymer fraction (PP2) form the matrix (PP), (d)transferring said matrix (M) in a third reactor, (e) polymerizing insaid third reactor in the presence of the matrix (M) propylene andethylene and/or C₄ to C₈ α-olefin obtaining an elastomeric propylenecopolymer (E), said matrix (M) and said elastomeric propylene copolymer(E) form the heterophasic propylene copolymer (RAHECO).
 37. Theheterophasic propylene copolymer (RAHECO) according to claim 21, whereinthe heterophasic propylene copolymer (RAHECO) has a flexural modulusmeasured according to ISO 178 in the range of 300 to 700 MPa.
 38. Theinjection molded article comprising a heterophasic propylene copolymer(RAHECO) according to claim
 21. 39. The thin wall packaging, comprisinga heterophasic propylene copolymer (RAHECO) according to claim
 21. 40.The use of a heterophasic propylene copolymer (RAHECO) as defined inclaim 21 for improving the toughness of an injection molded article,wherein the improvement is accomplished when the article has a Charpynotched impact strength as defined by equation (III)NIS>60−23.0×In(MFR)  (III) wherein “NIS” is the Charpy notched impactstrength according to ISO 179-1eA:2000 at 23° C. [in kJ/m²] of theheterophasic propylene copolymer (RAHECO), and “MFR” is the MFR₂ (230°C./2.16 kg) [in g/10 min] of the heterophasic propylene copolymer(RAHECO).